No doubt you read about a study showing that instead of increasing bone density as expected, it actually declined among 311 Canadians who took very high doses of vitamin D up to 10,000 units per day – for three years. None of the participants, who ranged in age between 55 and 70, had osteoporosis, and all were described as healthy.
The University of Calgary investigators who conducted the study surmised that taking high doses of vitamin D without additional calcium supplements (as I recommend) promotes the release of calcium from bone. They maintained that their results are consistent with those of a 2018 meta-analysis of 81 randomized clinical trials that concluded that oral vitamin D supplementation does not lead to reduced fractures, falls, or increases in bone density.
There’s much more to the story than that, however.
After analyzing the Canadian study results, Lise Alschuler, N.D., Assistant Director of the Fellowship in Integrative Medicine at my Center for Integrative Medicine at the University of Arizona, pointed out that ample clinical evidence supports the use of supplemental vitamin D plus calcium to lower the risk of fractures among older individuals who are deficient in D and at increased risk for falls. She referenced a 2007 meta-analysis of six randomized controlled trials representing 45,509 patients, which found that daily supplements of 700 to 800 international units of vitamin D plus daily supplements of 1000 to 1200 mg of calcium daily resulted in an 18 percent lower risk of hip fracture. Beyond that, she noted that vitamin D supplementation has other important health benefits, such as reduced risk of death from cancer.
It’s true that vitamin D supplementation, by itself, is unlikely to improve bone density and reduce the risk of osteoporotic fractures in older individuals with optimum blood levels of the vitamin. But there is plenty of evidence supporting the use of vitamin D plus calcium supplementation in older individuals whose blood levels of vitamin D are low.
Bottom line: I continue to recommend that everyone take 2000 IU of vitamin D daily, not only because it assists in the absorption of calcium and promotes bone mineralization but for its many other health benefits. It helps support the immune system, protects against a number of serious diseases including rickets and osteomalacia, and may provide protection from hypertension, psoriasis, multiple sclerosis, rheumatoid arthritis and cancer. I also recommend that postmenopausal women and those with a family history of osteoporosis supplement with no more than 500 to 700 mg of calcium (as calcium citrate) in two divided doses taken with meals for a total of 1,000-1,200 mg from all sources (including diet).
Andrew Weil, M.D.
Steven K. Boyd et al, “Effect of High-Dose Vitamin D Supplementation on Volumetric Bone Density and Bone Strength A Randomized Clinical Trial,” JAMA, August 27, 2019, doi: 10.1001/jam.2019.11889